of baltimore



AM. PHOTO-LITRO. CD. PLYA (OSBDRNES PROCESS.)

\ sra'rus WM. UUiFS or BALTIMORE, MARYLAND.

'SAFTYLVAIN FOR` STEAM- Bomans specificaties of 'Lett-ers Patent No. 3,202; atea July` as, 184s.

To all 'whom it may concern:

Be it known that I, VILLIAM DUrr, civil engineer, of the city of Baltimore, in the State of Maryland, have invented a new and useful manner of applying and regulating the weight of the safety-valve of a steanr engine, which improvement I denominate the hydrostatic weighted steam-.valve g and I do hereby declare that the followingis a full and exact description thereof. y

My improvement consists in causing a portion of the water from the boiler to constitute a portion of the weight that is to bear upon the safety valve of a steam engine. To effect this I usually make the body of the weight hollow, so as to admit water to pass into it from the boiler, there being a hollow tube, or stem, attached to such weight and forming a channel ofcommunicatio-n between the hollow body of said weight, and the boiler. In a weight constructed and arranged acording to my plan, the greater portion of the load upon the safety-valve may consist of that due to the weight itself, which may be increased to the desired extent by means of the water. Thus, supposing the hollow weight to weigh fifty pounds, and the capacity of the hollow part thereof to be such as to contain twelve pounds of water, the two weights combined will amount to sixty two pounds. While the water in the boiler remains at such height as to admit of the dipping of the hollow stem into it, the weight will be so situated as to become filled, or partially filled, with water, according to the pressure of the steam. Should this pressure increase beyond the destined amount, the water in the boiler continuing at its proper height, the safety-valve will be raised, as in other boilers; should the pressure continue, and the water become too low in the boiler, so that the stem of the hollow weight will no longer dip into it, the water will be dis charged from said weight, and the valve will be raised.

In the accompanying drawing, A., Figure l, represents a sectional view of a steam` boiler; B, a safety-valve, held down by the .weight on the lever C, in the ordinary way.

D, is the hollow weight bearing on the lever C; the hollow stem, E, of the weight, D, passes through a stuiiing box, F, into the boiler. A

G, G, may represent the ordinary water line, and H, H, the lowest point to which it II, within the boiler'.

is intended to descend. It will be seen that at this point, the water in the weight no longer being sustained by the dipping of the stem into that contained in the boiler, it will be discharged by its own gravity, and its pressure upon the valve will consequently be taken olf. The pressure of the steam upon the area of thelower end` of the stem, and upon the safety-valve, will then be both rendered effective, and will cause the latter to rise.

I propose, sometimes, to dispense with the weighted lever, and to cause the hollow weight and its stem to be so formed as to constitute the safety-valve. This arrangement is shown in Fig. 2. The under side of the body ofthe weight, D, is so formed as to constitute a conical valve, which is fitted to a seat F. The hollow stem, E, is to be made to work vertically by means of suitable guides, and when thus arranged, and the weight D, and its capacity to contain water,

are properly adjusted to the intended pressure, its operation will be the same with that described under the first modification.

In Fig. 3, I have represented a inode of employing the hydrostatic valve by causing the gravity of a portion o-f the water contained in the boiler to operate entirely within said boiler, so as to open the safety-valve whenever the water descends to its lowest safe level. C, is the valve lever connected to a suitable standard, or fulcrum, I, at one end, and having a rod J, which passes through a stuliing box, F, jointed to it at the other. The rod J, `is also jointed to a lever The lever K, works on a fulcrum at L, in the manner of a scale beam, and has suspended from its ends two dishes, M, and N. The tops of these dishes may be on a level with, or a little below, the ordinary water line G, Gr; and their bottoms even with the lowest water line, H, H. The dish N, has an opening in its bottom, as at U; and when the .water `descends in the boiler,.the dish N, will become lighter than M, and will consequently rise and carry with it the rod J, and the safety-valve, B.

Various other modifica-tions of the manner of employing ar portion 'of the water contained in a steam-boiler, so as to constitute a part of the loadingof a safety-valve, may be devised, but the foregoing will serve fully lto exemplify the principle `upon which the action of my valve isdependent, and the manner of carrying such principle into effect. the foregoing description- What I claim therein as new, and desire to secure by Letters Patent, is-,

The employment of a portion of the Water contained in a steam-boiler to constitute the Weight, or a part of the Weight7 by which a safety-valve is to be held down, and which Water .Will cease to constitute such Weight And having fully explained this in When it has descended to a given level; the 1C said Weight of Water being rendered effective by means of apparatus constructed and arranged substantially 1n the manner herein fully made known.

' WILLIAM DUFF. Witnesses:

JOHN F. MEREDITH, IVM. PETERS. 

